The exergy home has an extensive system of conduit. A comparison can
be made with the blood vessels system of birds and dolphins as described
by Julian Vincent, the so-called 'countercurrentsystem'. While bird feet
have built in heat exchanges so they won't freeze in the sometimes ice
cold water, the exergy home exchanges heat with its relative warm underground.
The development of a new district between Arnhem and Nijmegen (the KAN-region) offers the possibility to develop an alternative energy-infrastructure on city level. The Dutch government and a co-operation of power companies have made their goal to offer energy based on the exergy principle. One of the results of this initiative are the exergy-homes designed by Kristinsson.
'Exergy' is the utilisation of heat with low temperature and 'waste' energy. Exergy assumes that energy can have different levels of quality. Energy of a too high level of quality is used while a lower quality should be sufficient. For example, a natural gas flame of 1200 degrees Celsius is used to heat central-heating water to 90 degrees Celsius for the heating of an area, to 20 degrees Celsius. This leads to a loss of energy. Water of 25 to 40 degrees Celsius should be sufficient.
The exergie homes will be built on piles that will serve as heat exchangers. In energy saving the best result can be achieved by using the thermal mass of the underground, according to Kristinsson. The exergy homes have hollow piles in which water from two to ten metres deep can be drawn up. The water at that depth has a yearly average temperature of 10 degrees Celsius, in the winter the temperature is raised with a heat pump while in the summer the relative cold water is used as a means of cooling.
A parabolic sun collector on the roof controlled by a year clock takes care of warm water to bath and wash. Warm water that is left over is used for seasonal storage around the water filled piles in the ground. Sun cells provide electric energy, while passive sun-energy can be used by means of roof lights, sun bay windows and sun reflectors. Shutters are placed in front of the windows for extra insulation of the façade.
The typical Dutch home is very compact, yet there is a false space under every home of about 60 cm deep. Kristinsson gives this unused space a function as storage for warm wastewater and rainwater for the grey water circuit.
jv